NO other organisation is regarded with such respect as the United Nations. This is perhaps natural, for the UN embodies some of humanity's noblest dreams.

But, as the current scandal surrounding the UN's administration of the Iraq oil-for-food program demonstrates, and as the world remembers the Rwanda genocide that began 10 years ago, respect for the UN should be viewed as something of a superstition, with Secretary-General Kofi Annan as its false prophet. Not since Dag Hammarskjold has a UN leader been as acclaimed as Annan. Up to a point, this is understandable. Annan usually maintains an unruffled, dignified demeanour. He has charm and – many say – charisma. But a leader ought to be judged by his or her actions when important matters are at stake. Annan's failures in such situations are almost invariably glossed over.

Between 1993 and 1996, Annan was assistant secretary-general for UN peacekeeping operations and then undersecretary-general.

One of the two great disasters for which he bears a large share of the blame is the Serbian slaughter of 7000 people in the Bosnian town of Srebrenica, perhaps the worst massacre in post-war Europe.

In 1993, Bosnia's Muslims were promised that UN forces would protect them. This commitment was a precondition of their consent to disarm. The UN declared Srebrenica a "safe haven" to be "protected" by 600 Dutch UN troops.

In July 1995, Serb forces attacked. The UN did not honour its pledge. Annan's staff released evasive, confused statements. Oblivious, apparently, to the dreadfulness of the situation, they failed to sound the alarm properly and did nothing to intervene.

The Dutch fired not a single shot. NATO air power could have halted the Serbs, but Annan did not ask for NATO intervention.

Ratko Mladic, the Serb commander and war criminal, deported the women and children under the eyes of the UN, while capturing and murdering the men and adolescent boys.

No one should be surprised by the UN's inaction, because only the year before it had demonstrated utter incompetence in facing the fastest genocide in history – the slaughter of 800,000 Tutsis and moderate Hutus in Rwanda in just 100 days. UN forces in Rwanda in 1994 were Annan's responsibility before and during the crisis.

Annan was alerted four months before Hutu activists began their mass killings by a fax message from Romeo Dallaire, the Canadian general commanding UN forces in Rwanda. Dallaire described in detail how the Hutus were planning "anti-Tutsi extermination". He identified his source "a Hutu" and reported that arms were ready for the impending ethnic cleansing.

Dallaire requested permission to evacuate his informant and to seize the arms cache. Annan rejected both demands, proposing that Dallaire make the informant's identity known to Rwandan president Juvenal Habyarimana, a Hutu, even though the informant had expressly named the president's closest entourage as the authors of the genocide blueprint.

Annan maintained his extreme passiveness even after the airplane crash that killed Habyarimana, which signalled the genocide's start, helped by the indifference of the great powers.

One might think Annan far too compromised to become secretary-general but the UN doesn't work that way. Instead of being forced to resign after Rwanda and Srebrenica, he was promoted to the post.

That is the culture of the UN: believe the best of barbarians, do nothing to provoke controversy among superiors, and let others be the butt of criticism afterwards. Even subsequent revelations about Annan's responsibility for the disasters in Rwanda and Bosnia did not affect his standing. On the contrary, he was unanimously re-elected and awarded the Nobel Peace Prize.

The media sometimes ratchets up admiration for Annan by pointing out that his wife, Nane Annan, is Swedish and a close relative of Raoul Wallenberg. We are meant to infer that, on top of all his talents, Annan shares the ideals embodied during the last days of World War II by the foremost Swede of modern times.

But Wallenberg's name should make us even more dismayed about Annan's record. In Hungary, Wallenberg exploited every contact, resorting to shady tricks, bribes and other stratagems to save as many people as possible from the Holocaust. He never allowed himself to be duped by Hitler's cronies.

Perhaps no one's achievement should be judged by comparison with that of Wallenberg – a titan of strength, courage and perseverance.

Annan cannot plead he faced any risk to his safety, whereas Wallenberg in 1944 and 1945 was in constant peril. Nor can he excuse himself by saying no warnings were given, or that he lacked resources, or that he did not have the international position to intervene.

Annan had at his disposal all the instruments of power and opinion Wallenberg lacked. Yet, when thousands or hundreds of thousands of people were exposed to mortal threats he had the authority and duty to avert, alleviate, or at least announce, he failed.

Now, despite revelations about bribery in the UN's oil-for-food program for Iraq, the world is clamouring to entrust Annan with the future of more than 20 million Iraqis who survived Saddam Hussein dictatorship. That is because of who Annan is and what the UN has become: an institution in which no shortcoming, it seems, goes unrewarded.